A complete blood count, or CBC, is a blood test used to measure the number of blood cells in the body and the ratio of one type of blood cell to another in the bloodstream.This information is invaluable in assessing the overall health of the patient and in diagnosing various infections, diseases or disorders. It provides specific information about the following:
- Red blood cells which carry oxygen throughout the body
- White bloods cell which fight infection
- Platelets which assist in the blood-clotting process
- Hemoglobin which carries oxygen to the blood and aids in the clotting process
- The ratio of red blood cells to plasma in the blood, called a hematocrit
The complete blood count is essential in determining if the patient is in a good state of health since abnormal results may reveal blood disorders, such as anemia, leukemia, sickle cell disease, or the presence of infection. A complete blood count is often the first diagnostic test undertaken since it may be done during routine a physical examination. Complete blood counts are simple to obtain, necessitating only the withdrawal of a relatively small quantity of blood from the patient through a tiny hole in the vein. This process is called venipuncture. It is safe, quick, and almost painless.
Complete blood counts are obtained in order for the doctor to confirm the healthy results of a positive physical examination or to diagnose one of the following:
- Blood clotting disorder
- Blood abnormality such as anemia
- Other disease
Sometimes a blood smear test is done at the same time as the CBC. In a blood smear, a drop of blood is spread thinly across a microscopic slide and stained with a special dye. When the doctor looks at this slide under the microscope the number, shapes and sizes of the various blood cells are visible, giving the physician an even clearer understanding of any disease process. During a blood smear, for example, abnormally shaped cells may indicate the presence of sickle cell anemia.